Nano-Silicon@Exfoliated Graphite/Pyrolytic Polyaniline Composite of a High-Performance Cathode for Lithium Storage

In this paper, a Si@EG composite was prepared by liquid phase mixing and the elevated temperature solid phase method, while polyaniline was synthesized by the in situ chemical polymerization of aniline monomer to coat the surface of nano-silicon and exfoliated graphite composites (Si@EG). Pyrolytic polyaniline (p-PANI) coating prevents the agglomeration of silicon nanoparticles, forming a good conductive network that effectively alleviates the volume expansion effect of silicon electrodes. SEM, TEM, XRD, Raman, TGA and BET were used to observe the morphology and analyze the structure of the samples. The electrochemical properties of the materials were tested by the constant current charge discharge and cyclic voltammetry (CV) methods. The results show that Si@EG@p-PANI not only inhibits the agglomeration between silicon nanoparticles and forms a good conductive network but also uses the outermost layer of p-PANI carbon coating to effectively alleviate the volume expansion of silicon nanoparticles during cycling. Si@EG@p-PANI had a high initial specific capacity of 1491 mAh g(-1) and still maintains 752 mAh g(-1) after 100 cycles at 100 mA g(-1), which shows that it possesses excellent electrochemical stability and reversibility.

Automated summary

In this study, a Si@EG composite was prepared using liquid phase mixing and elevated temperature solid phase method, while polyaniline was synthesized to coat the surface of the composite. The coated composite effectively alleviates the volume expansion effect of silicon electrodes and forms a conductive network. The electrochemical properties of Si@EG@p-PANI were tested and it showed excellent stability and reversibility with a high initial specific capacity and maintenance of capacity after cycling.